Vacuum-controlled spark-timing device

ABSTRACT

A vacuum-controlled spark-timing device for combined use with a contact breaker of a gasoline engine, said device having a rotatable plate mounted for free rotation about a camshaft in a contact breaker housing, said rotatable plate having thereon a fixed contact point and a contact breaker lever pivotably mounted on said rotatable plate, said pivotable lever having thereon a cam follower in sliding contact with the cam surface of said camshaft and a movable contact point adapted to be brought into or out of electrically conductive contact with said fixed contact point upon rotation of said camshaft, a hermetically sealed casing mounted on said contact breaker housing and having a diaphragm dividing the interior of said casing into two chambers, a connecting rod sealingly extending through said casing and having one end pivotably connected to said rotatable plate and the other end secured to said diaphragm, one of said chambers being in communication with an air inlet conduit of said engine at a point upstream of a throttle valve mounted within said conduit and the other of said chambers being in communication with said conduit downstream of said throttle valve, whereby said diaphragm is displaced in one direction by the vacuum exerted to said one chamber during normal operation of said engine to cause said connecting rod to rotate said rotatable plate in one direction for thereby advancing the ignition timing of the engine and said diaphragm is displaced in the opposite direction by the vacuum exerted to said other chamber during idling or deceleration of said engine to cause said connecting rod to rotate said rotary plate in the opposite direction for thereby retarding the ignition timing.

United States Patent [72] lnventors Hisaji Okamoto PrimaryExaminer-Laurence M. Goodridge n- AltorneyCushman, Darby & CushmanYosiaki Takeda, Nagoya; Yosio Hukuhara, Yokohama, all of Japan [21]Appl. No. 832,191 ABSTRACT: A vacuum-controlled spark-timing device for[22] Filed June 11, 1969 combined use with a contact breaker ofagasoline engine, said [45] Patented Oct. 12, 1971 device having arotatable plate mounted for free rotation [73] Assignees Nippon DensoCompany Limited about a camshaft in a contact breaker housing, saidrotatable KariyahiJa n; plate having thereon a fixed contact point and acontact Kyosandenki Co., Ltd. breaker lever pivotably mounted on saidrotatable plate, said Tokyo, Japan pivotable lever having thereon a camfollower in sliding con- [32] Priority Oct. 5, 1968 tact with the camsurface of said camshaft and a movable con- [33] Japan tact pointadapted to be brought into or out of electrically [31] 43/72623conductive contact with said fixed contact point upon rotation of saidcamshaft. a hermetically sealed casing mounted on said contact breakerhousing and having a diaphragm dividing the interior of said casing intotwo chambers, a connecting rod sealingly extending through said casingand having one end 54 VAQUUM CONTROLLED SPARKJHMING DEVICE pivotablyconnected to said rotatable plate and the other end 4Claims3Dmwing Figssecured to said diaphragm, one of said chambers being in communicationwith an air inlet conduit of said engine at a [52] US- Cl 123/1 17 A,point upstream ofa throttle valve mounted within Said conduit 1 123M465A and the other of said chambers being in communication with [51] I11.Cl F02!) 5/10 Said conduit downstream of Said throttle Valve wherebySaid [50] held of Search 23/1 diaphragm is displaced in one direction bythe vacuum exerted 1171; 92/92 168 to said one chamber during normaloperation of said engine to cause said connecting rod to rotate saidrotatable plate in one [56] (defences cued direction for therebyadvancing the ignition timing of the en- UNITED STATES PATENTS gine andsaid diaphragm is displaced in the opposite direction 3,411,414 11/1968Brown et a1 7 92/168 X by the vacuum exerted to said other chamberduring idling or 3,447,518 6/1969 Walker 123/117.1 deceleration of saidengine to cause said connecting rod to 3,456,633 7/1969 Walker 123/117.1rotate said rotary plate in the opposite direction for thereby 3,486,59512/1969 Turner 123/1 17.1 retarding the ignition timing.

open position VACUUM-CONTROLLED SPARK-TIMING DEVICE BACKGROUND OF THEINVENTION Field of the Invention The present invention relates to avacuum-controlled spark- .timing device adapted to be mounted on aninternal combustion engine, that is, to a device for automaticallyregulating the ignition timing of an internal combustion engine inaccordance with the vacuum within the air inlet conduit of the engine.

It is well-known fact that, in the past, a great deal of harmfulcomponents such as hydrocarbon was contained in the gas exhausted from ageneral gasoline engine during idling or deceleration of the engine.Moreover, the contamination of the air due to these exhaust gases hasbeen serious problem to public health for the recent several years and,hence, a consideration has been earnestly made to solve this problem. Asa solution of this problem, it has been proposed to retard or defer theignition timing of an engine during idling or deceleration beyond theignition timing required by the engine so as to remarkably reduce thehydrocarbon contained in the exhaust gases. For this purpose, variouskinds of ignition-timing-retarding devices including vacuum-controlledignition timers have been devised. However, a vacuum-controlledignition-timing advancer is conventionally mounted on the contactbreaker housing towhich ignition-timing retarder of such kind is to besecured. The attachment of such a retarder in addition to theconventional ignition-timing advancer to the contact breaker will notonly give rise to an increase in expense but also be very inconvenientin physical viewpoint or, namely, in the viewpoint of space around theengine. Furthermore, independently mounted advances and retarders do nothave adequate vibrationproof characteristic to satisfy the requirementin durability.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a vacuumcontrolled spark-timing device which, while being ofsubstantially the same size as that of conventional vacuum-controlledignition-timing advancing device, serves as both ignition-timingadvancer and retarder.

It is another object of the present invention to provide avacuumcontrolled spark-timing device of the character as described inthe preceding paragraph and which can be manufactured at cost hardlyexceeding that of a conventional ignition-timing advancer.

It is a further object of the invention to provide a combinedvacuum'controlled spark-timing advancing and retarding device which canconveniently be mounted on a conventional gasoline engine of a givenautomobile.

It is a further object of the invention to provide a combinedignition-timing advancing and retarding device which can exhibit a goodvibrationproof characteristic.

A still further object of the present invention is to provide avacuum-controlled spark-timing device which may be selectively operableeither to advance or to retard the ignition timing of a gasoline engine.

According to the present invention, there is provided avacuum-controlled spark-timing device for use with a gasoline engine,which includes a single diaphragm adapted to be actuated by vacuumwithin an air inlet conduit of the engine, said diaphragm having anenclosed ignition-timing advancement chamber on one side of saiddiaphragm and an enclosed ignition-timing retardation chamber on theother side thereof, spring means within at least one of said chambersfor controlling the displacement of said diaphragm caused by the vacuum,and a connecting rod having one end pivotably connected to a rotatableplate in an associated contact breaker housing and the other end securedto said diaphragm. The ignition-timing advancement and retardationchambers have respective vacuum inlet ports which may be connectedthrough tubings to the air inlet conduit at the points downstream andupstream of a throttle valve mounted in the conduit, respectively.

The rotatable plate has mounted thereon a fixed contact point and apivotable contact breaker lever having thereon a cam follower in slidingcontact with the cam surface of a camshaft extending axially through therotatable plate for free relative rotation with respect to the latter.The contact breaker lever also has thereon a movable contact point inopposite relationship to the fixed contact point so that the movablecontact point may be brought into or out of electrically conductivecontact with the fixed contact point upon rotation of the cam surface onthe camshaft. With the above arrangement, a displacement of thediaphragm in one direction caused by the vacuum exerted to one of theenclosed chambers is transmitted through the connecting rod to therotatable plate which in turn is rotated in one direction with respectto the camshaft, with the result that the cam follower on the contactbreaker lever is shifted relative to the cam surface in' a directionopposite to the direction of rotation of the camshaft to advance thecontact-breaking operation of the lever for thereby advancing theignition timing of the engine. The above operation is performed duringnormal operation of the engine. During idling or deceleration of theengine, the vacuum is applied to the other of the chambers and, thus,the above-mentioned members are actuated all in the directions oppositeto the directions in the case of the above ignition-timing-advancingoperation and, hence, retardation or the ignition timing is achieved.

Means may be provided on a herrnetical casing for adjusting the actionof the spring means within one or both of the enclosed chambers tothereby precisely control the displacement of the diaphragm caused bythe vacuum introduced from the air inlet conduit, said casing comprisinga pair of unitary joined casing members which cooperate with thediaphragm to define the enclosed two chambers.

Other objects and features of the present invention will be made clearfrom the following description with reference to the accompanyingdrawings.

DESCRIPTION OF DRAWINGS FIG. 1 is a plan view of a contact breakerhaving mounted thereon a vacuum-controlled spark-timing device accordingto the present invention,

FIG. 2 is a longitudinal sectional view illustrating a firstembodimentof the device of the invention, and

FIG. 3 is a longitudinal sectional view illustrating the secondembodiment of the device of the invention.

Referring first to FIG. 1 and FIG. 2 which illustrate the firstembodiment of the device of the present invention, numeral 1 indicates acontact breaker housing within which a fixed baseplate 2 is rigidlymounted by means of screws 3. A camshaft 4 is disposed within thehousing I and is operatively connected to an engine (not shown) so as tobe rotated thereby in the direction indicated by an arrow shown inFIG. 1. A rotatable plate 5 is supported on the fixed baseplate 2 forfree rotation about the camshaft 4. On the rotatable plate 5 is rigidlymounted a supporting plate 6 by means of screws 7, which supportingplate has a breaker rod 8 pivotably. connected thereto by means of apivot pin and an electrically insulating sleeve therearound, Therotatable plate 5 has a fixed contact point 9 mounted on the supportingplate 6 in opposite relationship to a movable contact point 10 mountedon the forward end of the breaker rod 8. The latter has mounted thereona slider or cam follower 11 which will follow the rotational movement ofthe cam surface of the camshaft 4 so as to move the movable contactpoint 10 away from the fixed contact 9 for thereby breaking or shuttingoff the primary current in the ignition coil (not shown) when the camfollower 1.1 rides on each of the projections or rises on the camsurface.

Numeral 12 indicates a vacuum-controlled spark-timing device accordingto the present invention. The device 12 is secured through a mountingplate 13 to the housing 1 of the contact breaker by means of a screw 14.The device includes a connecting rod 15 having one end pivotablyconnected to the rotatable plate of the contact breaker by means of apin 16. The connecting rod has a reduced-diameter portion 15a adjacentthe other end of the rod with a shoulder formed between the portion 15aand the major portion of the rod 15. The connecting rod portion 150extends through the center of a circular diaphragm 17 and through thecenters of a pair of cup-shaped washers 18 and 19 disposed on theopposite sides of the diaphragm 17. The reduced-diameter portion 15a hasa threaded forward end on which a bar 20 having a threaded recess isthreadable mounted to fasten the washers 18 and 19 and the sandwicheddiaphragm 17 against the shoulder on the connecting rod 15.

A diaphragm 21 closely and sealingly surrounds the peripheral surface ofthe connecting rod 15 adjacent the shoulder. The diaphragm 21 has itsouter end sealingly bonded to an inner periphery of a supporting sleeve22 which is adapted to be fitted into the housing 1 of the contactbreaker. The other or inner end of the diaphragm 21 is also sealinglybonded to the bottom of the cup-shaped washer 18.

A generally cup-shaped casing member 24 having a vacuum inlet port 23 issealingly secured at the inner peripheral edge of central opening to theouter periphery of the supporting sleeve 22. At the side opposite to thecasing 24 with respect to the diaphragm 17, a cup-shaped casing member26 having a vacuum inlet port is sealingly secured at the innerperipheral edge of central opening to a sleeve member 27 having aclosure 28 threadably fitted into the outer end of the sleeve 27 with apacking ring 29 interposed therebetween. The casing members 24 and 26have their outer peripheries firmly secured or connected together withthe outer periphery of the diaphragm 17 firmly held between theconnected peripheries of the casing members, the casing members 24 and26 and the diaphragm 17 cooperating to define a pair of enclosedchambers 30 and 31 on the opposite sides of the diaphragm 17.

The sleeve 27 has a bottom or inner wall 27 formed with a centralaperture through which the rod 20 extends into the interior of thesleeve. Within the latter and around the rod 20 is disposed a pair ofinner and outer coiled compression springs 32 and 33 having their oneends urging a fiat washer 34 against the bottom 27' of the sleeve member27. The inner compression spring 32 is retained at the other end by anut 35 threadably mounted on the forward end of the rod 20. Also, theouter compression spring 33 is retained at the other end by a plate 36threadably fitted into the sleeve 27 and centrally apertured for thereasons which will become apparent later.

The vacuum inlet ports 23 and 25 of the casings 24 and 26 are connectedto the air inlet conduit 40 of an associated engine at points downstreamand upstream, respectively, of a throttle valve 41 in the conduit.

The device of the present invention having the aforestated constructionoperates in the following manner: Since the throttle valve of the engineis opened during ordinary operation of the engine, there existsatmospheric pressure within the air inlet conduit 40 at the point ofconnection of a tubing 42 from the vacuum inlet port 23 to the air inletconduit whereas vacuum is produced within said air inlet conduit at thepoint of connection of another tubing 43 from the vacuum inlet port 25to said air inlet conduit, which vacuum is exerted through said anothertubing 42 and the vacuum inlet port 25 to the enclosed chamber 31 tosuck or bias the diaphragm 17 rightwards. This displaces the diaphragm17 to a position at which said vacuum is balanced with the flexibilityof the compression spring 33. This displacement of the diaphragm 17 istransmitted through the connecting rod 15 and the pin 16 to therotatable plate 5 of the contact breaker for rotating the rotatableplate in the direction opposite to the direction indicated by the arrowshown in FIG. 1, with the result that the time at which the cam follower11 is reached by projections on the cam surface of the camshaft 4 isadvanced. Thus, an advancement of ignition timing is achieved.

The throttle valve is completely closed at idling or deceleration of theengine. In this condition of the engine, atmospheric pressure isabruptly exerted to the enclosed chamber 31 while the other chamber 30is supplied with vacuum, so that the diaphragm 17 is biassed ordisplaced leftwards to a position at which said vacuum is balanced withthe flexibility of the compression spring 32. This displacement of thediaphragm 17 rotates the rotatable plate 5 in the direction opposite tothe direction in the above-described instance, that is, in the directionindicated by the arrow in FIG. I. This rotation, therefore, achieves aretardation of ignition timing.

FIG. 3 illustrates the second embodiment of the present invention. Thedevice of the instant embodiment operates in the same manner as in thefirst embodiment. In this embodiment shown in FIG. 3, the parts similaror identical to those in the first embodiment are denoted by identicalnumerals. The greatest difference in structure of this embodiment fromthe device of the preceding embodiment is that while in the firstembodiment the compression springs 32 and 33 are both disposed withinthe enclosed chamber 31, the compression spring 32 in the instantembodiment is disposed within the enclosed chamber 30 and thecompression spring 33 is provided within the enclosed chamber 31. Inaddition, the threaded rod 20 in the first embodiment is replaced by acapnut 37 which urges cup-shaped washers 18 and 19 against a shoulderdefined by an enlarged portion 15b on the connecting rod 15, saidwashers being disposed in contact with the opposite sides of thediaphragm 17 in the central portion thereof. A threaded plate 38 issubstituted for the nut 35 in the first embodiment, the plates 38 beingthreadably fitted into the supporting sleeve 22 to retain thecompression spring 32 at its one end. A flat washer 39 is disposedaround the connecting rod 15 between the other end of the compressionspring 32 and another shoulder on the enlarged portion 15b formed on theside opposite to the above-mentioned shoulder. A spring retainer 40corresponding to the threaded plate 36 in the first embodiment isthreadably mounted on the closure 28 of the sleeve 27 to retain thecompression spring 33 at its outer end.

In the devices of the first and the second embodiments, any one ofadvanced and retarded ignition-timing characteristics may be obtainableby replacing the compression springs 32 and 33 with springs of differentspring constant. Furthermore, a precise regulation of advanced and/orretarded ignition-timing characteristics after the completion ofmounting of the devices may be carried out by appropriately adjustingthe positions of the nut 35 and the threaded plate 36 in the firstembodiment and of the threaded plate 38 and the spring retainer 40 inthe second embodiment. In addition, the device of the present inventionmay be operable either as a device only for advancing ignition timing inwhich case the vacuum inlet port 23 is always opened to atmosphere, oras a device only for retarding ignition timing in which instance thevacuum inlet port 25 is always opened to atmosphere.

As has been described in detail, the device of the present inventioncomprises a pair of enclosed chambers, one for the advancement ofignition timing and the other for the retardation of the ignitiontiming, formed on the opposite sides of a single diaphragm which isactuated or driven by the vacuum present within the air inlet conduit ofan engine. In addition, springs are mounted within at least one of theenclosed chambers to control the displacement of the diaphragm.Moreover, the latter is connected to a connecting rod for driving therotatable plate in the contact breaker housing. The present invention,therefore, provides an advantage that ignition-timing advancing andretarding effects can be achieved with a single device by introducingthe vacuum from the interior of the air inlet conduit into the enclosedignition-timing advancement chamber during nonnal operation of theengine and by introducing the vacuum into the enclosed ignition-timingretardation chamber during idling or deceleration of the engine. lt isfurther pointed out that the device of the present invention may be ofsubstantially equal size as that of conventional vacuum-controlledspark-timing-advancing device, with the result that the device caneasily and conveniently be mounted onto a given automobile. Moreover,since the ignition-timing advancing and retarding sections are unitedtogether into a single unit, a better vibrationproof characteristic maybe obtained. According to the present invention, a still furtheradvantage is also obtainable that the device of the invention may beindependently used either as an ignition-timing advancer or as anignition-timing retarder by selectively exposing any one of theignition-timing advancement and retardation chambers to atmosphere.

The present invention has been described and illustrated hereinabovewith reference to preferred embodiments. It should be understood thatthe above embodiments are only for illustrative purpose and theinvention is not limited to these embodiments buy may have variousmodifications and changes within the spirit and the scope of theinvention defined in the annexed claims.

What is claimed is:

l. A vacuum-controlled spark-timing device for use with an internalcombustion engine of the type that utilizes at least one ignition plug,said device comprising a casing, a diaphragm dividing the interior ofsaid easing into two chambers, a first chamber which has a first vacuuminlet port communicating with an air inlet conduit of said enginedownstream of a throttle valve mounted in said conduit, and a secondchamber which has a second vacuum inlet port communicating with said airinlet conduit upstream of said throttle valve, a con-- necting rodhaving one end pivotally connected to a rotary plate in an associatedcontact breaker housing and the other end secured to said diaphragm, anda pair of independent compression spring means provided within at leastone of said chambers and arranged such that only one of said springmeans acts on said connecting rod when said rod is moved in onedirection while only the other spring means acts thereon when said rodis moved in the opposite direction, whereby said diaphragm is biassed inone direction by the vacuum drawn through said second vacuum inlet porton said second chamber during normal operation of said engine to causesaid connecting rod to rotate said rotary plate in one direction foradvancing the spark timing of said engine whereas said diaphragm isbiassed in the other direction by the vacuum drawn through said firstvacuum inlet port on said first chamber during idling or decelerationoperation of said engine to cause said connecting rod to rotate saidrotary plate in the opposite direction for thereby retarding the sparktiming of said engine.

2. A vacuum-controlled spark-timing device as claimed in claim 1 whereinmeans are provided on at least one casing member for precisely adjustingthe spring forces of said spring means.

3. A vacuum-controlled spark-timing device as claimed in claim 2 whereinsaid spring means are a pair of compression coil springs disposed withinone of said chambers, the forces of said coil springs being adjustableby adjustable spring retainers, one of said retainers being threadablymounted on said casing while the other of said retainers is threadablymounted on said connecting rod.

4. A vacuum-controlled spark-timing device as claimed in claim 2 whereinsaid spring means are a pair of compression coil springs one springbeing disposed within each of said chambers, the forces of said coilsprings being adjustable by a pair of adjustable spring retainers eachthreadably mounted on said casing.

1. A vacuum-controlled spark-timing device for use with an internalcombustion engiNe of the type that utilizes at least one ignition plug,said device comprising a casing, a diaphragm dividing the interior ofsaid casing into two chambers, a first chamber which has a first vacuuminlet port communicating with an air inlet conduit of said enginedownstream of a throttle valve mounted in said conduit, and a secondchamber which has a second vacuum inlet port communicating with said airinlet conduit upstream of said throttle valve, a connecting rod havingone end pivotally connected to a rotary plate in an associated contactbreaker housing and the other end secured to said diaphragm, and a pairof independent compression spring means provided within at least one ofsaid chambers and arranged such that only one of said spring means actson said connecting rod when said rod is moved in one direction whileonly the other spring means acts thereon when said rod is moved in theopposite direction, whereby said diaphragm is biassed in one directionby the vacuum drawn through said second vacuum inlet port on said secondchamber during normal operation of said engine to cause said connectingrod to rotate said rotary plate in one direction for advancing the sparktiming of said engine whereas said diaphragm is biassed in the otherdirection by the vacuum drawn through said first vacuum inlet port onsaid first chamber during idling or deceleration operation of saidengine to cause said connecting rod to rotate said rotary plate in theopposite direction for thereby retarding the spark timing of saidengine.
 2. A vacuum-controlled spark-timing device as claimed in claim 1wherein means are provided on at least one casing member for preciselyadjusting the spring forces of said spring means.
 3. A vacuum-controlledspark-timing device as claimed in claim 2 wherein said spring means area pair of compression coil springs disposed within one of said chambers,the forces of said coil springs being adjustable by adjustable springretainers, one of said retainers being threadably mounted on said casingwhile the other of said retainers is threadably mounted on saidconnecting rod.
 4. A vacuum-controlled spark-timing device as claimed inclaim 2 wherein said spring means are a pair of compression coil springsone spring being disposed within each of said chambers, the forces ofsaid coil springs being adjustable by a pair of adjustable springretainers each threadably mounted on said casing.